The wavelength of the plant light is very suitable for the growth, flowering, fruiting of plants. Generally, indoor plants and flowers will grow worse and worse over time, mainly due to the lack of light exposure. By illuminating the plant with LED lights suitable for the spectrum required by the plant, not only can its growth be promoted, but the flowering period can also be extended and the quality of the flower can be improved. The application of this high-efficiency light source system to agricultural production such as greenhouses, greenhouses and other facilities can solve the disadvantages of insufficient sunshine leading to the decline in the taste of greenhouse vegetables such as tomatoes and cucumbers, and on the other hand, it can also make winter greenhouse tomato fruits and vegetables go on the market before and after the Spring Festival, so as to achieve the purpose of off-season cultivation.
Since junction temperature can be determined by average power dissipation, even large ripple currents have little effect on power dissipation. For example, in a buck converter, a peak-to-peak ripple current equal to the DC output current (Ipk-pk=Iout) adds no more than 10% of the total power loss. If the above loss levels are well exceeded, the AC ripple current from the power supply needs to be reduced to keep the junction temperature and operating life constant. A very useful rule of thumb is that for every 10 degrees Celsius decrease in junction temperature, semiconductor lifetime increases threefold. In fact, most designs tend to have lower ripple currents due to the inductor’s rejection. In addition, the peak current in the LED should not exceed the maximum safe operating current rating specified by the manufacturer.
When driving an LED through a buck regulator, the LED often conducts the AC ripple current and DC current of the inductor according to the selected output filter arrangement. This will not only increase the RMS amplitude of the current in the LED, but also increase its power consumption. This increases junction temperature and has a significant impact on the lifetime of the LED. If we set a 70% light output limit as the lifetime of the LED, then the lifetime of the LED is extended from 74 hours at 15,000 degrees Celsius to 40,000 hours at 63 degrees Celsius. The power loss of an LED is determined by multiplying the LED resistance by the square of the RMS current plus the average current multiplied by the forward voltage drop.
Below the LED turn-on threshold (the turn-on voltage threshold for white LEDs is approximately 3.5V), the current through the LED is very small. Above this threshold, the current is exponentially multiplied as a forward voltage. This allows the LED to be shaped as a voltage source with a series resistor with a warning that this model is only valid at a single operating DC current. If the DC current in the LED changes, the resistance of the model should also change to reflect the new operating current. At large forward currents, power dissipation in the LED heats up the device, which changes the forward voltage drop and dynamic impedance. It is very important to fully consider the heat dissipation environment when determining the impedance of the LED.
Adjustable brightness requires a constant current to drive the LED, which must be kept constant regardless of the input voltage. This is more challenging than simply connecting an incandescent bulb to a battery to power it.
Post time: Nov-16-2022